The use of blister packs to hold medicaments for inhalation devices, for example in bronchodilation therapy, is well known. The blister packs usually consist of a base sheet in which blisters are formed. The blisters are arranged on the base sheet and can be filled with medicament to be administered through use of an inhalation device. A lid sheet is applied to cover the filled blisters and the two sheets are sealed together to form a blister pack.
There can, however, be problems associated with methods of filling the blisters with medicament. Powder, particularly the drug component of the powder, can tend to be attracted to the base sheet surface rather than to the blister pockets. This attraction of the drug to the base sheet can result in inaccurate filling of the blisters, create mess and potentially cause problems with adherence of the lid sheet to the base sheet. Such filling methods may also require a large reservoir of powder, potentially resulting in waste of the medicament.
In earlier PCT Patent Application No. WO 00/71419, the Applicant described that the potential problem of powder adherence can be overcome by using a filling method utilising a perforated plate to mask the base sheet surface during filling to avoid covering this area with powder and a director (e.g. a director blade) to direct the powder into the perforations of the plate. The perforated plate is moved into contact with the appropriate areas of the blister strip during filling and then moved away at the end of the method and can be reused in each cycle. This filling method can also be used to fill other types of containers e.g. injection moulded plastic pockets, capsules or bulk containers.
The Applicant has now found that the above filling method may be improved when the perforated plate and director blade are moved in a rotary fashion relative to each other. When such a rotary relationship exists between these two components, faster methods of filling are enabled including those operable on a continuous rotary basis.